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Dahl and Nygaard's Simula-67 language [Birtwistle et al. 1973] introduced the notion of classes, objects, single inheritance, static methods, instance testing, typecase, and the prefix technique to implement static single inheritance. In addition it had coroutines and garbage collection. Cohen [1991] suggested the display for constant-time testing of class membership. Dynamic methods and multiple inheritance appeared in Smalltalk [Goldberg et al. 1983], but the first implementations used slow searches of parent classes to find method instances. Rose [1988] and Connor et al. [1989] discuss fast hash-based field- and method-access algorithms for multiple inheritance. The use of graph coloring in implementing multiple inheritance is due to Dixon et al. [1989]. Lippman [1996] shows how C++-style multiple inheritance is implemented. Chambers et al. [1991] describe several techniques to make classless, dynamically typed languages perform efficiently: pseudo-class descriptors, multiple versions of method instances, and other optimizations. Diwan et al. [1996] describe optimizations for statically typed languages that can replace dynamic method calls by static function calls. Conventional object-oriented languages choose a method instance for a call a.f(x,y) based only on the class of the method receiver (a) and not other arguments (x,y). Languages with multimethods [Bobrow et al. 1989] allow dynamic method lookup based on the types of all arguments. This would solve the problem of orthogonal directions of modularity discussed on page 93. Chambers and Leavens [1995] show how to do static type-checking for multimethods; Amiel et al. [1994] and Chen and Turau [1994] show how to do efficient dynamic multimethod lookup.

Nelson [1991] describes Modula-3, Stroustrup [1997] describes C++, and Arnold and Gosling [1996] describe Java.

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